assets.xml

<?xml version="1.0" encoding="UTF-8"?>
<odoo>
    <template id="assets_backend"
              name="web_duplicate_visibility backend assets"
              inherit_id="web.assets_backend">
        <xpath expr="."
               position="inside">
            <script type="text/javascript"
                    src="/web_duplicate_visibility/static/src/js/duplicate_visibility.js">
            </script>
        </xpath>
    </template>

    <template id="qunit_suite"
              name="web_duplicate_visibility qunit assets"
              inherit_id="web.qunit_suite">
        <xpath expr="//html/head"
               position="inside">
            <script type="text/javascript"
                    src="/web_duplicate_visibility/static/test/duplicate_visibility.js">
            </script>
        </xpath>
    </template>
</odoo>